The invention relates to a fuse, as used in medium- and high-voltage installations.
Fuses of the generic type are known for example from U.S. Pat. Nos. 4,319,212 and 4,638,283. There, a fuse element in strip form, connecting the electrical terminals arranged at the opposite ends of a cylindrical fuse chamberxe2x80x94there may also be a number of fuse elements disposed in parallelxe2x80x94is wound helically onto a carrier consisting of electrically insulating material and provided with ribs. At locations at which a fuse element rests on one of the ribs there is arranged in a depression of the latter a burn-off element which burns, evolving quenching gas, as soon as an arc is formed, or the burn-off element is ignited by an electric signal.
Although fuses of this type are suitable for building up relatively high voltages, a rapid and reliable interruption of high currents is not possible since the blowing of the arc is only weak and not very effective.
A fuse according to an embodiment of the invention allows the rapid and reliable interruption of short-circuit currents of high power. The fuse has a fuse chamber with a first electrical terminal and a second electrical terminal at opposite ends of the fuse chamber. At least one fuse element of electrically conducting meltable material connects the first electrical terminal to the second electrical terminal through the fuse chamber. A triggerable quenching gas source produces a quenching gas flow in the fuse chamber. The invention provides a fuse in which not only is the fuse element interrupted but the arc thereby produced is also blown effectively enough for it to be rapidly quenched.
The fuse according to the invention can therefore also be used in high-voltage installations with nominal voltages of 72 kV and more, at nominal currents of over 2 kA. Its short-circuit disconnection capability is of the same order of magnitude as that of high-voltage switches. It can therefore be also be used in switching installations as a dropout fuse in series with switching device.